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Fighting fire with a steam machine

By Ben Crystall

A CHANCE discovery has transformed an engine intended for speedboats into a powerful firefighting tool that douses flames with jets of water mist.

When used for boats, the engine works by injecting steam through a rear-facing, ring-shaped nozzle into a cylindrical chamber. As the steam emerges at three times the speed of sound, it rapidly condenses, generating a shock wave that pulls in water through an intake and expels it from the rear, generating thrust (New Scientist, 1 February 2003, p 19).

The new application emerged when engineers at its manufacturer, Pursuit Dynamics in Royston, Hertfordshire, …